Traditionally, in-line roller skates and ice skates generally include an upper shoe portion secured by a base to a frame supporting wheels or an ice blade. The upper shoe portion provides the support for the skater's foot, while the frame rigidly attaches the wheels or blade to the shoe. When skating on traditional skates, particularly during thrusting, difficulties are encountered in efficiently transferring the thrust from the skater to the ground. The inefficiencies are due in part, to the frame being rigidly attached to the base of the skate, which decreases the effectiveness of the thrust, as well as the comfort for the skater.
Efficiently imparting thrust to the skate during the skating stroke is especially important to speed skaters. Because of the rigid attachment of the frame to the base, speed skaters are coached not to plantarflex their ankle during the push-off phase of the stroke. The term “plantarflex” is commonly used in the art to describe the rotation of the foot relative to the leg, where the fore foot moves distally from the leg. No plantarflexion at the ankle keeps the blade flat on the ice and prevents the tip of the blade from digging into the ice, thereby causing an increase in friction and reducing the skater's speed. If, however, the skater is permitted to plantarflex his or her ankles during the skate stroke, the fore foot will be able to move distally and allow the calf muscles to generate more power during the skate stroke when compared to a stroke where plantarflexion is prevented or discouraged. Thus, a skate that permits ankle plantarflex should allow a skater to generate more power and speed, in addition to reducing the risk of digging the blade's tip into the surface the skater is traversing.
Prior attempts at allowing ankle plantarflexion have resulted in complicated linkage mechanisms that move the instantaneous point of rotation between the boot and blade forward as the heel lifts. Such a linkage mechanism often results in a skate that is too heavy because of the multiple links. Other attempts at permitting ankle plantarflexion have used a single-hinge joint between the blade and boot, thereby hingedly connecting the blade to the boot. The hinge is located below the boot, between the metatarsal head and toe end of the boot. While a single-hinge point attachment system is lighter, current models fail to prevent medial to lateral motion of the blade relative to the boot when the heel is lifted because of a narrow hinge, thus resulting in an unstable skating stroke.
Also, when the heel is lifted, the force from the boot to the blade is transferred through the hinge point. Thus, the skater cannot change the location of the center of pressure on the blade. This produces an unstable platform from which the skater can apply thrust through the blade.
An additional drawback to skates having a single hinge joint stems from the shoe portion of the skate. As briefly noted above, skates traditionally have a boot or shoe portion that has a rigid or semi-rigid base that impedes the foot from flexing at the ball of the foot during the skating motion, thereby restricting the natural movement in the foot, which occurs during locomotion, and preventing a skater from generating the maximum power from the skate stroke.
Thus, there exists a need for a skate that would permit ankle plantarflexion during a skating stroke, that is also lightweight, stable, and a boot that can allow flexion at the ball of the foot. U.S. Pat. No. 6,082,744 to Allinger et al. addresses these issues to overcome the limitations currently encountered by providing a skate that has a first hinge member defined in the metatarsal head region to provide flexing of the shoe base and a second hinge member that is located substantially at the toe end of the boot to allow plantar flexion of the ankle. The second hinge permits the shoe, as a whole, to pivot in relation to the horizontal surface. However, Allinger et al. failed to address the problem of lateral or sideways stability of the shoe in relation to the frame when the skater plantar flexes the ankle. During the skating stroke involving plantar flexing, the heel of the shoe is moved up and away from the frame with the only attachment being at the front of the shoe, making the heel prone to lateral movement. Furthermore, some skaters may desire to have control over which hinge should flex first. The double-hinged skate as described in the '744 patent has the ability to flex both at the shoe base and to flex the shoe, as a whole, with respect to the frame. However, the construction of the skate described in the '744 patent makes it difficult to have control over which hinge flexes first. Some skaters may desire to flex the metatarsal region of the shoe base prior to plantar flexing the entire shoe in order to provide a more natural movement. The present invention provides a flexing shoe base, double hinged skate, capable of plantar flexing with a stabilizing rear heel hinge. Furthermore, the skate in accordance with the present invention, makes it possible for a skater to substantially flex the metatarsal region of the shoe base first, followed by flexing the shoe, as a whole, with respect to the frame.